1 Overview

GNU LibreJS —an add-on for GNU IceCat and Mozilla Firefox— detects
and blocks nonfree nontrivial JavaScript while allowing its execution on
pages containing code that is either trivial and/or free.

Many websites run nontrivial JavaScript on your computer. Some use it
for complex tasks; many use it gratuitously for minor jobs that could be
done easily with plain HTML. Sometimes this JavaScript code is
malicious. Either way, the JavaScript code is often nonfree. For
explanation of the issue, see "The JavaScript
Trap"(http://www.gnu.org/philosophy/javascript-trap.html).

If you care about freedom in your computing, and don’t wish to let all
and sundry make you run nonfree programs, now you can prevent it by
using LibreJS.